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RE: Buffer Sort explanation

From: Deepak Sharma <sharmakdeep_oracle_at_yahoo.com>
Date: Mon, 8 Aug 2005 11:52:30 -0700 (PDT)
Message-ID: <20050808185230.80697.qmail@web52811.mail.yahoo.com>


The temp_disable did get rid of the TEMP table creation step in the star_transformation plan, but tkprof still shows a very high BUFFER SORT, and the query failed w/ 'snapshot too old' after 3 Hrs. With the temp table step, it did finish in 2 1/2 hrs or so.


      105       BITMAP MERGE
   352207        BITMAP KEY ITERATION
128553935           BUFFER SORT
  1627265          TABLE ACCESS BY GLOBAL INDEX ROWID
OBJ#(1433369) PARTITION: ROW LOCATION ROW LOCATION
  1627265           INDEX RANGE SCAN OBJ#(1433605)
(object id 1433605)
   352207         BITMAP INDEX RANGE SCAN
OBJ#(3441108) PARTITION: 1 177 (object id 3441108)

> Hi
>
>
>
> > Rows Operation
> > =========
> =======================================
> >a) 105 BITMAP MERGE
> >b) 351549 BITMAP KEY ITERATION
> >c) 127009880 BUFFER SORT
> >d) 1607720 TABLE ACCESS FULL
> SYS_TEMP_4254956840
> >e) 351549 BITMAP INDEX RANGE SCAN
> OBJ#(3441108)
>
>
>
> I'm not able to explain you what the BUFFER SORT
> exactly does in this case (it should only get the
> data from the temporary table and prepare them for
> the "join" with the index on the fact table...
> Anyway, each time I have a problem with a star
> transformation with temporary tables I try to
> disable the temporary tables (they were/are buggy!).
> Therefore try
> star_transformation_enabled=temp_disable.
>
>
>
>
>
> Regards,
>
> Chris
>
>
>
>



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Received on Mon Aug 08 2005 - 14:45:41 CDT

Original text of this message

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